From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 25 Feb 2022 17:35:12 GMT
Subject: Re: [PATCH 2/7] commit-graph: fix ordering bug in generation numbers
Message-ID: <xmqqwnhietnz.fsf@gitster.g>
In-Reply-To: <756fd005-637d-a067-9949-e87fc15b3bf6@github.com>

Derrick Stolee <derrickstolee@github.com> writes:

> It is very subtle, which is why it took me a while to debug this
> issue once I managed to trigger it.
>
>>     for each commit ctx->commits.list[i]:
>>         continue if generation number has been computed for it already
>
> This is the critical line in the current version. This includes
> "continue if the generation number was loaded from the previous
> commit-graph file." This means we under-count when building from
> an existing commit-graph with overflows.
>
> If we insert an increment here, then we risk double-counting. I
> should have described this better.

Ah, that obviously I missed.  Thanks.